1211.0590 (Jeng-Da Chai et al.)

Restoration of the Derivative Discontinuity in Kohn-Sham Density
Functional Theory: An Efficient Scheme for Energy Gap Correction    [PDF]

Jeng-Da Chai, Po-Ta Chen

Based on a simple and physically motivated approximation to an expression for the derivative discontinuity (DD) of the exchange-correlation (XC) energy functional in Kohn-Sham density functional theory (KS-DFT), we show that the DD can be approximately expressed as an explicit universal functional of the ground-state density and the KS lowest unoccupied molecular orbital density, allowing the direct evaluation of the DD in the standard KS method without extra computational cost. The fundamental gap can be predicted by adding the estimated DD to the KS gap. This scheme is shown to be accurate in the prediction of the fundamental gaps for a wide variety of atoms and molecules. In addition, possible extensions of this scheme for improved accuracy are also discussed.

View original: http://arxiv.org/abs/1211.0590